Coaxial cable television systems have been in widespread use for many years and extensive networks have been developed. The extensive and complex networks are often difficult for a cable operator to manage and monitor. A typical cable network generally contains a headend which provides content to a cable modem termination system (CMTS) containing several receivers, each receiver is usually connected to modems of many subscribers, e.g., a single receiver may be connected to hundreds of modems. In many instances the operator will cable multiple receivers together to serve a particular area of a town or city.
Whenever the CMTS detects that the frequency a receiver is currently using has communication problems, such as having high noise levels, a cable operator may move one or more modems to a different receiver. Cable operators often use Load Balancing Groups to equalize the load of the traffic across receivers, and Spectrum Groups to allocate multiple upstream frequencies to a receiver. In order to have receivers belong to the same Load Balancing Group or Spectrum Group they must be physically connected together. Multiple frequencies in a Spectrum Group may be used for frequency agility. The CMTS can determine which “backup” frequency is the best to use and retune the receiver in the Spectrum Group to the new frequency with no interruption to cable subscribers.
Cable networks are also increasingly carrying signals which require a high quality and reliability of service, such as voice communications or Voice over IP (VoIP) communications. Any disruption of voice or data traffic is a great inconvenience and often unacceptable to a subscriber. If a receiver is running fine, then all the modems and media terminal adapters (MTAs) will be passing data and voice without problems. However if one receiver fails in the CMTS unit, or an external device goes bad in the CMTS, then all of the modems and MTAs will deregister from that receiver, causing subscriber loss of service. If there are no other receivers in the same spectrum group or load balancing group available, then these modems will not register again until an operator in the headend re-wires the RF or replaces the failed CMTS receiver card.
Accordingly, there exists a need to prevent loss of service to subscribers when a receiver fails.